﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using System.Drawing;
namespace Com.CMS263.Web
{
    public partial class ValidateCode : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            CreateImage.DrawImage();
        }

        public class CreateImage
        {
            public CreateImage()
            {
                //
                // TODO: 在此处添加构造函数逻辑
                //
            }
            public static void DrawImage()
            {
                CreateImage img = new CreateImage();
                string code = img.RndNum(4);

                HttpContext.Current.Session["code"] = img.RndNum(4);

                img.CreateImages(code);
            }
            /// <summary>
            /// 生成验证图片
            /// </summary>
            /// <param name="checkCode">验证字符</param>
            private void CreateImages(string checkCode)
            {
                int iwidth = (int)(checkCode.Length * 15);
                System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 25);
                Graphics g = Graphics.FromImage(image);
                g.Clear(Color.White);
                //定义颜色
                Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Blue, 

Color.Brown, Color.DarkCyan, Color.Purple };
                //定义字体 
                string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
                Random rand = new Random();
                //随机输出噪点
                for (int i = 0; i < 150; i++)
                {
                    int x = rand.Next(image.Width);
                    int y = rand.Next(image.Height);
                    g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);
                }
                //输出不同字体和颜色的验证码字符
                for (int i = 0; i < checkCode.Length; i++)
                {
                    int cindex = rand.Next(7);
                    int findex = rand.Next(5);
                    Font f = new System.Drawing.Font(font[findex], 13,

    System.Drawing.FontStyle.Bold);
                    Brush b = new System.Drawing.SolidBrush(c[cindex]);
                    int ii = 4;
                    if ((i + 1) % 2 == 0)
                    {
                        ii = 2;
                    }
                    g.DrawString(checkCode.Substring(i, 1), f, b, 3 + (i * 12), ii);
                }
                //画一个边框
                //g.DrawRectangle(new Pen(Color.Gray, 0), 0, 0, image.Width - 1, image.Height -1);

                //输出到浏览器
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                HttpContext.Current.Response.ClearContent();

                HttpContext.Current.Response.ContentType = "image/Jpeg";
                HttpContext.Current.Response.BinaryWrite(ms.ToArray());
                g.Dispose();
                image.Dispose();
            }

            /// <summary>
            /// 生成随机的字母
            /// </summary>
            /// <param name="VcodeNum">生成字母的个数</param>
            /// <returns>string</returns>
            private string RndNum(int VcodeNum)
            {
                string Vchar =
    "1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z";
                string[] VcArray = Vchar.Split(',');
                string VNum = ""; //由于字符串很短，就不用StringBuilder了
                int temp = -1; //记录上次随机数值，尽量避免生产几个一样的随机数
                //采用一个简单的算法以保证生成随机数的不同
                Random rand = new Random();
                for (int i = 1; i < VcodeNum + 1; i++)
                {
                    if (temp != -1)
                    {
                        rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));
                    }
                    int t = rand.Next(VcArray.Length);
                    if (temp != -1 && temp == t)
                    {
                        return RndNum(VcodeNum);
                    }
                    temp = t;
                    VNum += VcArray[t];
                }
                return VNum;
            }
        }
    }
}
